Typically two radios co-located on the same computer platform, particularly laptops, notebook and netbook computer systems, need high isolation to function optimally. This high isolation between the two radios prevents the two radios from interfering with the other radio's reception. Conventionally, this essential isolation is typically achieved through a high isolation between the two radios' antennas and highly selective filters on the radio receiver side of conventional radio architecture.
As more and more radios and antennas are integrated in a computer system, there is an increasing difficulty in achieving a high isolation between closely spaced antennas. As a result, a more stringent filter requirement is forced upon the wireless module. However, due to cost and real estate constraints, the performance of the front-end filter on the wireless module is usually compromised. Consequently a major portion of radio co-existence issues in current computer systems, and more particularly mobile computing systems such as laptops, notebooks and netbooks, are caused by front-end saturation due to strong out-of-bound (OOB) interference from other embedded radios operating at a nearby frequency band.
Additionally, in a computer system comprising a single radio, excessive filtering is usually required to reject spurious emission of transmission in order to obtain regulatory compliance. This filtering is sometimes found to be inadequate in a radio module prototype or hard to achieve on a low cost radio solution. Currently, to solve these problems at a modular level usually incurs significant cost increases and time to market delays.